MEDICAL AIR FITTINGS ARE THE STANDARD USED IN MOST OPERATING ROOMS TO DRIVE PNEUMATIC TOOLS...EVEN THOUGH NITROGEN IS THE GAS DRIVING THE INSTRUMENT.Please reference detailed images to determine proper fitting. Sometimes you will find N2 or AIR stamped on fittings.The typical scenario is:A Nitrogen panel on the wall has a MALE NITROGEN DISS fitting (1121-4), An extension hose connects to the Nitrogen panel with a FEMALE NITROGEN DISS fitting (1217HT), The other end of the extension hose has a FEMALE AIR SCRADER (SCF-16-17). The pneumatic instrument connects to extension hose with a MALE AIR SCHRADER fitting (SCH-16-17)